Marin County: Agate Beach and Duxbury Reef

San Francisco: Marin Headlands - Mt Tamalpais - Point Reyes

Agate Beach County Park and Duxbury Reef Preserve are located in Bolinas, CA. Duxbury Reef is the largest soft shale reef in California, and one of the largest shale reefs in all of North America. Duxbury Reef is part of the Gulf of the Farallones National Marine Sanctuary, encompassing over 1,280 square miles of ocean and shoreline along the northern California coast. The sanctuary protects 33 marine mammal species, including 20% of California's breeding harbor seal population. Agate Beach covers 6.6 acres, with nearly two miles of shoreline at low tide.